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PET 2001 keyboard issue + instability

Actually it's changed since I posted that address earlier in the thread, now it's 0 0 1C00 01 01. But I did swap some of the RAM chips around so that's probably to be expected.
 
So, that fault is data bit 4 of 6550 RAM device J8.

The test is trying to set all of the bits to a '0' and that bit is stuck at a '1'.

I would just check pin 13 of J8 (if it is in a socket).

EDIT: Ah, my PETTESTER will tell you the faulty IC device and data bit. If you have moved J8 to I8 then that is what will happen if the data bit is faulty within the IC. You did make a note of what you swapped didn't you :)?

Swapping the RAM chips around when PETTESTER has found a fault only serves to confuse the human! Fix the faulty device that is indicated.

Dave
 
So with the new RAM chip installed I get no errors in the DRAM test (let it run 200 times).

The issue with the keyboard had already seemingly disappeared before replacing the bad RAM chip so I don't think this has fixed it, and I suspect it'll crop up again in the future.
 
You have my PETTESTER tool now to check the keyboard if the fault returns.

So does the PET now work OK.

Don't forget to test out the cassette port (if you have a cassette unit of course) and the IEEE488 port (there is a simple "type in" BASIC program for that available).

Dave
 
daver2 said:
You have my PETTESTER tool now to check the keyboard if the fault returns.

So does the PET now work OK.

Don't forget to test out the cassette port (if you have a cassette unit of course) and the IEEE488 port (there is a simple "type in" BASIC program for that available).

Dave
Click to expand...
Both cassette ports work, and I’ve even managed to get the built-in port working semi-reliably. So for right now everything seems good!
 
Yes, it works with my PET SD card readers.

There are a few spots on the case with chipped/scraped/rusted off paint I’d like to do something about. I am extremely hesitant about using paint on the case, although I would NOT be painting the entire thing, just the affected spots. I may end up not doing anything at all, but I’m curious to hear if anyone here has any experience painting PETs.
 
Oswald said:
Yes, it works with my PET SD card readers.

There are a few spots on the case with chipped/scraped/rusted off paint I’d like to do something about. I am extremely hesitant about using paint on the case, although I would NOT be painting the entire thing, just the affected spots. I may end up not doing anything at all, but I’m curious to hear if anyone here has any experience painting PETs.
Click to expand...
I've had one completely stripped and powder-coated, but I'd only do that in extreme cases.
For a few spots, if you don't want to paint it, try some automotive wax or protective coating on the bare metal spots to prevent rust.
 
daver2 said:
@Hugo Holden has I think.

Dave
Click to expand...
I haven't re-painted a PET yet.

I have repainted and repaired many plastic and or rusty cases on other things though.

If it is a steel cased PET and there are rust spots, you can just treat the spots only. Put a small amount of tape around the perimeter of each spot (low adhesive stickyness type paint masking tape, though this is not to mask the paint) the tape protects the surrounding paint while you remove as much rust as you can with 600 grade paper. Then with a small brush apply a small amount of Fertan organic rust converter to each spot , this turns the remaining rust in the pits in the steel into an inactive organic compound. (without doing that the rust will simply reappear under the new paint).

Then remove the tape and with a very small fine artists brush apply new paint over the area and try to feather it in so its less obvious. For this to work you need an exact color match. You can now buy cheap colorimeters and take the paint color data to the local paint store and they can mix it up to an exact match.The paint should have a flat or just under Satin, not gloss. And it will take 1 to 3 layers over the treated rust spot to make it optically less visible.

If it isn't a good match or not done well, obviously an entire re-paint will work better because it will look spotty like the PET is recovering from a case of Chicken Pox.

If its a plastic top PET, the entire top can be re-sprayed easily with Dupli-Color auto paint, the solvent etches into the existing paint and exposed plastic areas and it won't flake off and it is thin enough that the original surface texture is maintained too.
 
For rust removal I use a product called "Iron Free".
It's a green chemical meant for cars, but it removes rust without damaging the paint.
I learned about it from an old Adrian Black video and I've used it many times on a few PETs and PET disk drives.

For outdoor use, since it smells really bad (IMHO). Spray it on and let it sit. The green will turn red/purple as it absorbs the loose iron.
After a while, rinse with water and check if the rust is all gone, if not, repeat. You should be left with bare steel after and clean edges around the paint.
The smell doesn't linger on the parts but it will linger on your hands, so I wear gloves.
 
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